The present invention relates to a controlled electromagnetic induction detonation system for initiation of a detonatable material, and in particular, but not exclusively, for decoupled in-hole initiation of a detonatable material.
Throughout this specification and claims the term xe2x80x9cdetonatable materialxe2x80x9d is used in a broad and generic sense to include any initiating device such as an electrical detonator, fuse, fusehead, electric match; and, any energetic material such as explosive, propellant and the like.
Explosives and propellants are used in the mining and construction industries in many different applications including tunnelling, stoping, civil excavations and boulder breaking.
In order to initiate the explosive or propellant some type of detonator or fuse is required. The detonator or fuse in turn can be set off either electrically or mechanically. The present invention is concerned with the wireless electric initiation of a detonator or fuse or other energetic material.
Most commonly, the initiating of an electric detonator or fuse is accomplished by a physical conductor such as a wire pair connected at one end to the detonator and at an opposite end to an electric power supply via a switch. When the switch is closed, current flows through the wire to initiate the detonator or fuse.
Such type of electric initiation system can sometimes be set off prematurely or accidentally through the induction of electric currents in the conductors by stray electromagnetic fields or, through faults in the initiating electric circuit comprising the wires, switch and power supply.
Another electric initiation system available under the brand name Magne-Det is known in which a pair of electric conductors that are attached to a detonator extend through a coil through which a current flows. The current flowing through the coil induces a current to flow through the conductors which in turn is used as the detonation current. However this system is also clearly prone to accidental or premature activation by picking up stray electromagnetic fields.
All of these initiation systems require manual connection of the detonator to a source of initiation energy.
It is the object of the present invention to provide a detonation system in which the likelihood of accidental initiation of a detonatable material is substantially reduced. It is a further object of the present invention to provide a system for wireless non-contact initiation of a detonatable material.
According to the first aspect of the present invention there is provided a controlled electromagnetic induction detonation system for initiating a detonatable material, the system including:
an automated radio charge (ARCH) module for delivering an electric detonation current to a detonatable material, said ARCH module having no permanent on board power supply including a power circuit for extracting power by means of electromagnetic induction from a electromagnetic field generated remotely from the ARCH module, the power circuit providing operational power for the ARCH module and the electric detonation current, and means for receiving and decoding radio transmitted control signals including a FIRE code, the verified receipt of which causes the ARCH module to deliver said current to and thereby initiate the detonatable material.
Preferably the means for receiving and decoding the control signal extracts the control signal from said electromagnetic field.
Preferably said control signal includes an ARM code and the means for receiving and decoding, upon receipt, decoding and verification of said ARM code, initiates a timer in said ARCH module to time a predetermined period in which said ARCH module must receive, decode and verify said FIRE code in order to deliver said detonation current to the detonatable material, and in the absence of which, said ARCH module automatically shuts down for a second predetermined period.
Preferably said ARCH module further includes an output switch through which said electronic detonation current must flow in order to initiate the detonatable material, said switch configured to provide a short circuit output to the detonatable material until receipt and verification of said FIRE code, in which instance, said switch is operated to remove said short circuit and allow the electronic detonation current to flow to the detonatable material.
Preferably said system further includes a transducer unit having a power supply for supplying power to electromagnetic field generating means for generating said electromagnetic field and radio transceiver means for radio transmitting said control signals to the ARCH module.
Preferably said transducer unit further includes means for impressing said control signals onto said electromagnetic field so that said radio transceiver means transmits both said electromagnetic field and said control signals to said ARCH module.
Preferably said transducer unit includes a mode switch switchable between a LOCAL mode and a REMOTE mode of operation, wherein in said LOCAL mode of operation, a user can manually input instructions to said transducer unit for radio transmission to said ARCH module and wherein in said REMOTE mode of operation, a user can input instructions to said transducer unit via a remote controller unit.
Preferably said transducer unit includes means for manual entry of instructions and a timer means both operationally associated with said mode switch whereby on switching said mode switch to the LOCAL mode, a user must enter via said entry means a valid identification number recognised by said transducer unit within a predetermined period of time timed by said timer means in order for further user instructions to be acted upon by said transducer unit, and in the absence of the entry of a valid identification number within said time period said transducer unit automatically shuts down so as to be non responsive to user input instructions for a second period of time timed by said timer means.
Preferably said transducer unit includes an ARM switch functional when said transducer unit is in the LOCAL mode of operation which, when activated causes said electric field generating means to generate said electromagnetic field.
Preferably said transducer unit includes a FIRE switch functional when said transducer unit is in the LOCAL mode of operation and which when activated within a predetermined time period after activation of the ARM switch causes the transducer unit to transmit the FIRE code to the ARCH module.
Preferably said system further includes a stemming bar for stemming a hole in which said ARCH module and detonator can be deposited and wherein said transducer unit includes a coil for generating said electromagnetic field, said coil mounted on or in the stemming bar so that lines of magnetic flux pass through the stemming bar and link with the power circuit to transfer operational power to the ARCH module by electromagnetic induction.
Advantageously the stemming bar is reusable.
Preferably said system further includes a remote controller unit by which a user can communicate instructions to said transducer unit from a location remote from said transducer unit.
Preferably said remote controller unit includes means for the manual entry of instructions by which a user must enter a valid identification number within a predetermined time period in order for said remote controller to establish a radio communication link with said transducer unit. Although in an alternate embodiment the remote controller can be key-switch operated.
Preferably said remote controller unit includes processor means for generating a unique identification code word which is continuously transmitted until an acknowledgment signal is received from said transducer unit corresponding to said identification code word, and wherein in the absence of receipt of said acknowledge signal within a predetermined time period said remote controller unit enters a RESET mode in which a user must once again enter a valid identification number to reinitiate the establishment of the radio communication link with said transducer unit. Preferably said remote controller unit further includes an ARM switch which upon activation, when a radio communication link has been established with said transducer unit, causes the remote controller unit to transmit an ARM code to transducer unit upon which said transducer unit generates said electromagnetic field. However in an alternative embodiment the remote controller can be hard-wired to the transducer unit.
Preferably the ARM code is transmitted by said remote controller to said transducer unit is different to the ARM code sent by said transducer unit to said ARCH module.
Preferably said transducer unit sends an acknowledgment signal to said remote controller unit upon receipt of the ARM code and said transducer unit thereafter initiates its timer means to time a first period within which to receive a FIRE code from said remote controller unit, wherein the absence of receipt of said FIRE code within said first period said transducer unit automatically shuts down for a second period of time.
Preferably said remote control unit includes a FIRE switch, which, when activated causes the remote control unit to transmit a FIRE code to said transducer unit which in turn upon on verified receipt thereof retransmits the FIRE code to said ARCH module.
Preferably the FIRE code transmitted by the remote controller to transducer unit is different to the FIRE code retransmitted by the transducer unit to the ARCH module.
According to another aspect of the present invention there is provided a controlled electromagnetic induction detonation system for decoupled in-hole initiation of an detonatable material, said system including:
an automated radio charge (ARCH) module coupled to a detonatable material and deposited in a hole formed in a hard material, the ARCH module having no permanent on board power supply but including a power circuit for extracting by means of electromagnetic induction operational power from a remotely generated electromagnetic field, the power circuit providing operational power for the ARCH module and arranged to generate a detonation current deliverable to the detonatable material, and means for receiving and decoding radio transmitted control signals including a FIRE code, the verified receipt of which causes delivery of the detonation current to the detonatable material;
a stemming bar for stemming the hole in which the energetic material and ARCH module are deposited; and,
a transducer unit for radio transmitting said control signals, said transducer unit having a coil for generating the electromagnetic field, the coil mounted on or in the stemming bar to effect the transfer of operational power to the ARCH module by electromagnetic induction.